Or search: rue, grief, mourn, grieve, regret, remorse, sadness, mourning, attrition, heartache, contrition, heartbreak, bereavement, compunction, unhappiness
2 Syllables: SU
abo, Arno, aro, Austro, auto, Barlow, borrow, Bravo, cargo, cargoes, Carlo, Caro, charcoal, follow, grotto, hollow, lago, largo, Malo, Marco, morrow, Moscow, motto, Otto, Paulo, Roscoe, sorrows, Strabo, swallow, wallow
3 Syllables: USU
Apollo, bravado, Chicago, Dorado, embargo, Leonardo, Morocco, mulatto, Palazzo, Ricardo, Romano, soprano, staccato, tomato, tomorrow, tomorrow's
4 Syllables: UUSU
Colorado, Santiago

Found 48 words across 3 groupings. Skipped 3 excess words of a similar stem.